This invention relates to a method of encapsulating oils and oil-soluble materials, such as vitamins A, D, and E, which dispenses with the use of gelatins. More particularly, it relates to a method of producing ingestible microcapsules comprising a matrix of substantially water-insoluble shape-retaining alginate gel held together by salt bridges between the carboxyl groups of the alginate.
There are many known prior art methods of encapsulating oleophilic substances. Methods of encapsulating oil-soluble vitamins are disclosed, for example, in U.S. Pat. Nos. 2,183,053; 2,218,591; 2,643,209; 2,650,895; 2,897,119; 3,058,728; 3,099,602; 3,202,731; 3,293,132; 3,608,083; 3,749,799; 3,819,838; and 3,143,475. The vast majority of these and other vitamin encapsulating procedures involve the use of gelatins which are solidified about droplets of vitamin oils by rapidly lowering the temperature and subsequent dehydration.
While methods such as those disclosed in the patent literature set forth above have achieved some significant commercial success, difficulties have sometimes been encountered in rapidly inducing solidification of the encapsulating material. Furthermore, substantial quantities of heat are normally required in the course of gelatin-based processes in order to effectively dissolve the gelatin and to dehydrate the capsules produced.